Max Dynamic Response Header Size (bytes) ???

I seem to have problems with sites which try to set a larger cookie.
Would a dynamic response header which is too large be logged somewhere?
The sites show only some part of the page while they show the whole page if I just remove the setcookie-call.
Could it be that I just hit this limit?
Would it be possible to allow larger numbers than 8K there so one could experiment with it?

I get only a "premature end of response headers" in the error-log nothing more.
As I get only half of the page through lsws but running php-cgi (the same which is running the fcgi-backend with the same config) on the command-line with the same script I get the full page back, I can only guess that its related to lsws.
I can try to manually generate such a long setcookie-call. Will come back to you tomorrow if I succeed.

That error message means a FCGI protocol error, not the limit has been reached. It happens when PHP process crashed before sending the whole response header back to lsws, but you should not get half of the page if that is the case. Debug logging should be helpful.

You can just hard code the cookie along with the html page in a php script.